JP6145274B2 - Brushless motor drive device - Google Patents

Description

  The present invention relates to a drive device for a brushless motor, and relates to a drive device for driving a three-phase brushless motor without a sensor.

  In Patent Document 1, in a three-phase synchronous motor, an induced voltage (pulse induced voltage) of a non-energized phase induced by a pulse voltage is detected, the induced voltage is compared with a reference voltage, and the comparison result is determined. A drive system for a synchronous motor that sequentially switches energization modes is disclosed.

JP 2009-189176 A

  By the way, the pulse induced voltage of the non-energized phase is detected while the pulse voltage is applied to the two phases. However, since the pulse induced voltage fluctuates immediately after the start of voltage application, the duty ratio of the pulse voltage is small. (If the pulse width, which is the voltage application time is short), the pulse induced voltage is sampled within the fluctuation period, which may cause erroneous detection of the pulse induced voltage and erroneously determine the switching timing of the energization mode. There was sex.

In addition, the pulse-induced voltage of the non-energized phase changes depending on the duty ratio of the pulse voltage, and if the duty ratio is small, the voltage becomes lower than the voltage detection resolution, and it is impossible to determine the switching timing of the energized mode. There was a possibility of becoming.
On the other hand, in order to reduce the rotation speed of the motor, it is necessary to reduce the duty ratio. Therefore, it is difficult to reduce the motor rotation speed while suppressing the occurrence of step-out.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a drive device that can drive a brushless motor at a low rotational speed while suppressing occurrence of step-out.

Therefore, in the present invention, when the motor rotation speed is decreased, the electrical angle that is the switching cycle of the selection pattern is increased if the duty ratio of the pulse width modulation signal is decreased to a set value .

  According to the above invention, when the electrical angle of the switching period of the energization mode is increased, the motor torque at the same duty ratio is decreased and the motor rotation speed is decreased. Therefore, the motor rotation speed is further decreased while suppressing the occurrence of step-out. It becomes possible to make it.

It is a block diagram which shows the structure of the hydraulic pump system in embodiment of this invention. It is a circuit diagram showing composition of a motor control device and a brushless motor in an embodiment of the present invention. It is a flowchart which shows switching control of the electricity supply pattern of the brushless motor in embodiment of this invention. It is a flowchart which shows switching control of the electricity supply pattern of the brushless motor in embodiment of this invention. It is a figure which shows the characteristic of N value with respect to the motor rotational speed and minimum average duty ratio in embodiment of this invention. It is a time chart which shows the characteristic of the duty ratio for every detection frequency (N value) of position information in the embodiment of the present invention. It is a figure for demonstrating the fall of the minimum average duty ratio by the fall of the detection frequency in embodiment of this invention. It is a figure which shows an example of the characteristic which cannot reduce a rotational speed to a target by the fall of the detection frequency in embodiment of this invention. It is a flowchart which shows the setting control of the duty ratio for every PWM period in embodiment of this invention. It is a figure which shows the switching characteristic of the electricity supply mode in the electricity supply pattern A in the embodiment of this invention, and the electricity supply pattern B. FIG. It is a figure which shows the motor torque in the electricity supply pattern A and the electricity supply pattern B in embodiment of this invention. It is a figure which shows the correlation with the minimum average duty ratio and electricity supply pattern A and B in embodiment of this invention. It is a flowchart which shows the change control of the duty ratio accompanying the switching of the electricity supply pattern of the brushless motor in embodiment of this invention, and the said switching. It is a flowchart which shows the change control of the duty ratio accompanying the switching of the electricity supply pattern of the brushless motor in embodiment of this invention, and the said switching. It is a figure for demonstrating the difference in the torque characteristic by the switching timing of the electricity supply mode in the electricity supply pattern B in embodiment of this invention. It is a flowchart which shows delay control of the switching timing of the electricity supply mode in the electricity supply pattern B in embodiment of this invention. It is a flowchart which shows 3 steps | paragraphs of detection frequency switching in embodiment of this invention, and switching control of the electricity supply pattern for every detection frequency. It is a flowchart which shows 3 steps | paragraphs of detection frequency switching in embodiment of this invention, and switching control of the electricity supply pattern for every detection frequency. It is a flowchart which shows 3 steps | paragraphs of detection frequency switching in embodiment of this invention, and switching control of the electricity supply pattern for every detection frequency. It is a figure which shows the correlation with 3 steps switching of the detection frequency in embodiment of this invention, and the minimum average duty ratio. It is a flowchart which shows the control which switches the electricity supply pattern of the brushless motor in embodiment of this invention according to a rotation fluctuation | variation. It is a flowchart which shows the control which switches the electricity supply pattern of the brushless motor in embodiment of this invention according to a rotation fluctuation | variation. It is a flowchart which shows the detection control of the rotation fluctuation | variation in embodiment of this invention.

Embodiments of the present invention will be described below.
FIG. 1 is a block diagram showing a hydraulic pump system of an automatic transmission for an automobile to which a brushless motor driving device is applied.
The hydraulic pump system shown in FIG. 1 includes a mechanical oil pump 6 driven by the output of an engine (internal combustion engine) (not shown) and a motor as an oil pump that supplies oil to the transmission mechanism (TM) 7 and the actuator 8. And an electric oil pump 1 to be driven.

The electric oil pump 1 is operated, for example, when the engine is stopped by an idle stop, supplies oil to the transmission mechanism 7 and the actuator 8, and suppresses a decrease in hydraulic pressure during the idle stop.
The electric oil pump 1 is driven by a directly connected brushless motor (three-phase synchronous motor) 2, and the brushless motor 2 is controlled by a motor control unit (MCU) 3 based on a command from an AT control unit (ATCU) 4. The The motor control device 3 is a drive device that drives the brushless motor 2.

The electric oil pump 1 driven by the brushless motor 2 supplies the oil in the oil pan 10 to the speed change mechanism 7 and the actuator 8 via the oil pipe 5.
During the engine operation, the mechanical oil pump 6 driven by the engine is operated, and oil is supplied from the mechanical oil pump 6 to the transmission mechanism 7 and the actuator 8. At this time, the brushless motor 2 is in an off state (stopped) State), and the check valve 11 blocks the oil flow toward the electric oil pump 1.

On the other hand, when the engine is stopped by the idle stop, the mechanical oil pump 6 is stopped and the oil pressure in the oil pipe 9 is lowered. Therefore, in synchronization with the engine idle stop, the AT control device 4 issues a motor start command to the motor. It transmits to the control apparatus 3.
Upon receiving the motor activation command, the motor control device 3 activates the brushless motor 2 to rotate the electric oil pump 1 and starts the oil pumping by the electric oil pump 1.

When the discharge pressure of the mechanical oil pump 6 decreases while the discharge pressure of the electric oil pump 1 exceeds the set pressure, the check valve 11 is opened, and the oil is supplied to the oil pipe 5 and the electric oil pump 1. Circulates through the route of the check valve 11, the speed change mechanism 7, the actuator 8, and the oil pan 10.
The brushless motor can be, for example, a brushless motor that drives an electric water pump used to circulate engine cooling water in a hybrid vehicle or the like, and the device that the brushless motor drives is not limited to an oil pump, Further, the brushless motor is not limited to a motor mounted on an automobile.

FIG. 2 is a circuit diagram illustrating an example of the brushless motor 2 and the motor control device 3.
The motor control device 3 includes a motor drive circuit 212 and a controller 213 provided with a microcomputer, and the controller 213 communicates with the AT control device 4.
The brushless motor 2 is a three-phase DC brushless motor (three-phase synchronous motor) and includes U-phase, V-phase, and W-phase three-phase windings 215u, 215v, and 215w in a cylindrical stator (not shown), A permanent magnet rotor (rotor) 216 is rotatably provided in a space formed in the center of the stator.

The motor drive circuit 212 includes a circuit in which switching elements 217a to 217f including antiparallel diodes 218a to 218f are connected in a three-phase bridge, and a power supply circuit 219. The switching elements 217a to 217f are, for example, FETs. Composed.
The control terminals (gate terminals) of the switching elements 217a to 217f are connected to the controller 213, and the controller 213 controls on / off of the switching elements 217a to 217f by pulse width modulation PWM.

The drive control of the brushless motor 2 is performed without using a sensor that detects position information of the rotor, and further, switching between sine wave driving and rectangular wave driving is performed according to the motor rotation speed.
The sine wave drive is a method of driving the brushless motor 2 by applying a sine wave voltage to each phase. In this sine wave drive, while the rotor position information is obtained from the induced voltage (speed electromotive voltage) generated by the rotation of the rotor, the motor rotational speed is adjusted during the detection period of the rotor position by the speed electromotive voltage. The rotor position is estimated based on the calculated rotor position and the PWM duty, the three-phase output set value is calculated, and the direction and strength of the current are controlled by the difference in the interphase voltage to flow the three-phase alternating current. .

Further, the rectangular wave driving is a method of driving the brushless motor 2 by sequentially switching a selection pattern (energization mode) of two phases to which a pulse voltage is applied among the three phases according to a predetermined switching timing. In this rectangular wave drive, the position information of the rotor is obtained from the voltage (transformer electromotive voltage, pulse induced voltage) induced in the non-conduction phase by applying a pulsed voltage to the conduction phase, and the switching timing of the conduction mode is detected. To do.
Here, since the output level of the speed electromotive voltage detected for position detection in the sine wave drive decreases as the motor rotation speed decreases, the accuracy of position detection decreases in the low rotation range. On the other hand, the pulse induced voltage detected for position detection in the rectangular wave drive can detect position information even in a low rotation range including the motor stop state.

  Therefore, in a high rotation range where the position information can be detected with sufficient accuracy by sine wave drive (a region where the motor rotation speed is higher than the set value), the brushless motor 2 is driven by sine wave drive, and sufficient accuracy is obtained by sine wave drive. In the low rotation range where the position information cannot be detected in (a region where the motor rotation speed is lower than the set value, including when starting), the brushless motor 2 is driven by rectangular wave driving.

Hereinafter, the rectangular wave drive, which is a feature of the present invention, will be described in detail.
The flowcharts of FIGS. 3 and 4 show the flow of rectangular wave drive control by the controller 213. Note that the routines shown in the flowcharts of FIGS. 3 and 4 are executed by interruption every predetermined minute time.

In the flowcharts of FIGS. 3 and 4, in step S301, it is determined whether any of the target motor rotational speed MStg and the actual motor rotational speed MS is equal to or higher than the set speed MSSL.
The set speed MSSL is a threshold value of the motor rotation speed MS for switching the detection frequency of the rotor position information. As shown in FIG. 5, the set speed MSSL is detected in a speed range where the motor rotation speed MS is higher than the set speed MSSL. An N value (N = integer and N ≧ 1) defining the frequency is N1, and in a speed range lower than the set speed MSSL, the N value is N2 (N1 <N2).

Here, the setting of the position information detection frequency will be described in detail.
As shown in FIG. 6, the detection frequency of the rotor position information is defined as a value of N when position information is detected only once in N PWM periods.
Here, if N = 1, rotor detection (pulse-induced voltage detection) is performed every PWM cycle. If N = 2, as shown in FIG. After detecting the rotor, the detection of the rotor is stopped for one period, and the position detection of the rotor is repeated in the next period.

  Further, if N = 3, as shown in FIG. 6B, after detecting the rotor, the detection of the rotor is stopped for two cycles, and the position of the rotor is detected in the next cycle. Further, if N = 4, as shown in FIG. 6B, after detecting the rotor, the detection of the rotor is stopped for three cycles, The position detection of the rotor is repeatedly performed in the next cycle, and the detection frequency of the position information (pulse induced voltage) decreases as the value of N increases.

  In the rectangular wave drive, as described above, the rotor position information is obtained based on the pulse induced voltage induced in the non-energized phase by applying the pulsed voltage to the energized phase, but immediately after the voltage application is started, the pulse induced voltage is obtained. Therefore, it is necessary to detect the pulse-induced voltage while avoiding the fluctuation period, and if the duty ratio (%) is small (pulse width, on-time is short), the pulse-induced voltage reduces the voltage detection resolution. There is a possibility that the determination of switching timing of the energization mode (detection of position information) becomes impossible.

Therefore, the minimum duty ratio (pulse width lower limit value) DminA that can perform voltage detection while avoiding the fluctuation period of the pulse induced voltage and generate a pulse induced voltage exceeding the resolution of voltage detection is set, and this minimum The energization control is not performed at a duty ratio lower than the duty ratio DminA.
However, if the duty ratio for each PWM cycle is limited to the minimum duty ratio DminA or more, the motor rotation speed obtained when the duty ratio is set to the minimum duty ratio DminA becomes the minimum rotation speed of the brushless motor 2, and the minimum rotation speed is It becomes impossible to reduce the motor rotation speed below.

  Therefore, acquisition of rotor position information (in other words, detection of pulse-induced voltage for position information acquisition) is not performed every PWM cycle (not N times N = 1), By setting the period for acquiring the rotor position information and the period for not acquiring the position information, and reducing the detection frequency, the duty ratio of the period in which the position information is not acquired is set to the minimum duty ratio DminA. As a result, the duty ratio is lowered on average while the motor rotational speed can be further lowered while acquiring the rotor position information.

For example, as shown in FIG. 6A, the setting of N = 2, the duty ratio A = DminA, and the setting of the duty ratio B <DminA are repeated every PWM cycle, and the duty ratio A = DminA Sometimes the rotor position information is acquired, and when the duty ratio B <DminA, the rotor position information is not acquired, and the rotor position information is obtained once every two PWM periods. get.
In this case, since the position information of the rotor is acquired in a cycle in which the duty ratio A is the minimum duty ratio DminA, voltage detection can be performed while avoiding the fluctuation period of the pulse-induced voltage, and the voltage detection resolution is exceeded. A pulse-induced voltage can be generated, and the position of the rotor can be detected with sufficient accuracy.

On the other hand, as shown in FIG. 7, the duty ratio B when position detection is not performed is set to a value lower than the minimum duty ratio DminA. Therefore, the average duty ratio can be set to a value lower than the minimum duty ratio DminA. The average duty ratio when the duty ratio B without detection is 0% is the lowest average duty ratio Davmin that can be realized. When N = 2, DminA / 2 is the lowest average duty ratio Davmin.
Similarly, the minimum average duty ratio Davmin that can be realized when N = 3 is Davmin = DminA / 3.

  The energization mode switching period (ms) based on the rotor position information becomes longer as the rotation speed of the brushless motor 2 decreases, and the lower the motor rotation speed, the longer the acquisition period of the rotor position information. As shown in FIG. 8, the motor rotation speed can be further reduced by increasing the value of N as the motor rotation speed decreases to reduce the position information detection frequency and reducing the minimum average duty ratio Davmin.

In step S301, the detection frequency (N value) is switched by determining whether either the target motor rotation speed MStg or the actual motor rotation speed MS is equal to or higher than the set speed MSSL. ing.
If either the target motor rotation speed MStg or the actual motor rotation speed MS is equal to or higher than the set speed MSSL, the process proceeds to step S302, and the value of N that defines the detection frequency is set to N1 (N1 ≧ 1). Thus, the duty ratio for each PWM cycle is determined according to N1.

On the other hand, if both the target motor rotation speed MStg and the actual motor rotation speed MS are lower than the set speed MSSL, the process proceeds to step S312 and the value of N that defines the detection frequency is set. N2 (N2> N1 ≧ 1) is set, and the duty ratio for each PWM cycle is determined according to N2.
The determination of the duty ratio in step S302 and step S312 is performed according to the flowchart of FIG.

In step S401, for example, the applied voltage is determined based on the deviation between the actual motor rotational speed MS and the target motor rotational speed MStg, and in the next step S402, a target duty ratio Dtg for applying the applied voltage is calculated.
In step S403, it is determined whether the target duty ratio Dtg is equal to or greater than the minimum duty ratio DminA.

Here, if the target duty ratio Dtg is equal to or greater than the minimum duty ratio DminA, the position information can be detected for each PWM period by giving the pulse width of the target duty ratio Dtg for each PWM period. Then, the target duty ratio Dtg is set to the duty ratio for each PWM cycle as it is.
On the other hand, if the target duty ratio Dtg is less than the minimum duty ratio DminA, the process proceeds to step S405, and the detection timing of the rotor position information is set according to the N value currently assigned. For example, if N = 2, the position information of the rotor is detected at a rate of once every two PWM periods.

Next, in step S406, the duty ratio A in the PWM cycle for detecting the rotor position information is set to the minimum duty ratio DminA, and in step S407, the duty in the PWM cycle in which the rotor position information is not detected. The ratio B (B ≧ 0%) is calculated according to the N value and the target duty ratio Dtg.
For example, if N = 2, B = 2 × Dtg−DminA, and the duty ratio B in the PWM period in which the rotor position information is not detected is calculated. If N = 3, A + B + B = DminA + B + B = 3 * Dtg, and B = (3 * Dtg-DminA) / 2, the duty ratio B in two PWM periods in which the rotor position information is not detected is calculated.

That is, in step S407, the duty ratio B in the PWM cycle in which the rotor position information is not detected is calculated as B = (N × Dtg−DminA) / (N−1).
In the calculation of B = (N × Dtg−DminA) / (N−1), when “N × Dtg−DminA” becomes 0 or less, the PWM cycle in which the position information of the rotor is not detected. The duty ratio B at is set to 0%. As a result, the minimum average duty ratio Davmin becomes Davmin = DminA / N.

Here, as shown in FIG. 8, an N value is assigned in advance for each motor rotation speed range, and for each N value, a minimum realizable duty ratio Davmin is determined. Depending on the characteristics of the brushless motor 2, As indicated by a dotted line in FIG. 8, an average duty ratio Dav that is lower than the minimum average duty ratio Davmin may be required to obtain the target motor rotation speed MStg.
In the characteristic (characteristic 2) of the brushless motor 2 indicated by a dotted line in FIG. 8, the motor rotational speed MS is lower than MS (1) and higher than MS (2), the average duty ratio Dav is set to the lowest average duty ratio Davmin. It cannot be realized without lowering.

However, while it is necessary to maintain the minimum duty ratio DminA as the duty ratio in the period for performing position detection, the average duty ratio Dav is not reduced even if the duty ratio in the period in which position detection is not performed is reduced to 0%. It only decreases to the lowest average duty ratio Davmin, and in the motor rotation speed range at that time, it is necessary to set N = 1 from the request of the position information detection cycle, and if the N value is increased, the position information is detected. There is a possibility that the cycle becomes too long and the switching of the energization mode is delayed and the step-out occurs.
Therefore, after step S303 and after step S313, processing is performed when the motor rotational speed MS cannot be reduced to the target rotational speed MStg even if the average duty ratio is reduced to the lowest average duty ratio Davmin.

In step S303, it is determined whether or not the current energization pattern is an energization pattern A that switches the six energization modes (A1) to (A6) every electrical angle of 60 degrees.
In the rectangular wave driving of the present embodiment, the energization pattern A is set as a standard (default) energization pattern.

  As shown in FIG. 10, in the energization pattern A, in the energization mode (A1), current flows from the U phase to the V phase, and in the energization mode (A2), current flows from the U phase to the W phase. In mode (A3), current flows from the V phase to the W phase, in energization mode (A4), current flows from the V phase to the U phase, and in the energization mode (A5), from W phase to the U phase. In the energization mode (A6), current flows from the W phase to the V phase, and in the order of A1 → A2 → A3 → A4 → A5 → A6 → A1 →.. Switch the energization mode with.

  Here, if the angular position of the U-phase coil is the reference position (angle 0 deg) of the rotor, the angular position of the rotor that switches from the energization mode (A3) to the energization mode (A4) is 30 deg. The angular position of the rotor that switches from the mode (A4) to the energization mode (A5) is 90 deg, and the angular position of the rotor that switches from the energization mode (A5) to the energization mode (A6) is 150 deg. The angular position of the rotor that switches from the mode (A6) to the energization mode (A1) is 210 deg, and the angular position of the rotor that switches from the energization mode (A1) to the energization mode (A2) is 270 deg. The angular position of the rotor that switches from the mode (A2) to the energization mode (A3) is set to 330 deg.

On the other hand, as the energization pattern, an energization pattern B having a larger electrical angle of the energization mode switching period than the energization pattern A is set.
As shown in FIG. 10, the energization pattern B includes an energization mode (B1) in which current flows from the U phase to the W phase, an energization mode (B2) in which current flows from the V phase to the U phase, and V to V It is an energization pattern which switches the energization mode (B3) which sends an electric current toward a phase for every electrical angle 120deg.
Then, the angle position of the rotor for switching from the energization mode (B1) to the energization mode (B2) is set to 330 deg. Which is the same as the angle for switching from A2 to A3 in the energization pattern A, and energization is performed from the energization mode (B2). The angle position of the rotor for switching to the mode (B3) is set to 90 deg as the angle for switching from A4 to A5 in the energization pattern A, and the energization mode (B3) is switched to the energization mode (B1). The angular position of the rotor is set to 210 deg which is the same as the angle at which A6 → A1 is switched in the energization pattern A.

That is, in the energization mode A and the energization mode B, switching from the energization mode in which current flows from the U phase to the W phase is performed at an angular position of 330 deg and from the V phase toward the U phase. Switching from the energization mode for supplying current to the next energization mode is performed at an angular position of 90 deg, and switching from the energization mode for supplying current toward the V phase from the W phase to the next energization mode is performed at an angular position of 210 deg. Done in
The angle at which the energization mode is switched is detected by comparing the pulse induced voltage of the non-energized phase with the threshold corresponding to the energized mode at that time, and the timing at which the pulse induced voltage of the non-energized phase crosses the threshold. The

If it is determined in step S303 that the phase energization is controlled according to the energization pattern A, the process proceeds to step S304, and the deviation ΔMS between the target motor rotation speed MStg and the actual motor rotation speed MS (ΔMS = target motor rotation speed MStg−actual motor). It is determined whether or not the rotational speed MS) is equal to or less than a negative predetermined value ΔMSSL (ΔMSSL <0), that is, whether or not the actual motor rotational speed MS is higher than the target motor rotational speed MStg.
Here, if ΔMS> ΔMSSL, it is not necessary to switch from the energization pattern A (60 deg switching) to the energization pattern B (120 deg switching). In other words, the actual motor rotation speed MS is set to the energization pattern A. In this state, it is possible to approach the target motor rotation speed MStg, and the energization control with the energization pattern A is continued by ending this routine as it is.

On the other hand, if ΔMS ≦ ΔMSSL, the actual motor rotation speed MS may not be decreased to the target motor rotation speed MStg unless the switching from the energization pattern A to the energization pattern B is performed. move on.
In step S305, the latest detected value (current value) of the actual motor rotation speed MS and the actual motor rotation speed MS at the previous execution time of this routine (the actual motor rotation speed at a time point before the execution cycle of this routine). Whether or not the actual motor rotational speed MS is stagnant in a state higher than the target motor rotational speed MStg is determined by determining whether or not the absolute value ΔtMS of the difference between the actual motor rotational speed MS and the target motor rotational speed MStg Determine.

Here, if ΔtMS> ΔtMSSL, the actual motor rotational speed MS has changed, and may approach the target motor rotational speed MStg in the future. Continue energization control.
On the other hand, if ΔtMS ≦ ΔtMSSL, the actual motor rotational speed MS is stagnant in a state higher than the target motor rotational speed MStg, and the process proceeds to step S306.

In step S306, it is determined whether or not the state where the actual motor rotation speed MS is higher than the target motor rotation speed MStg has been stagnating for a predetermined time TSL or more.
When the state where the actual motor rotation speed MS is higher than the target motor rotation speed MStg has been stagnating for a predetermined time TSL or more, the average duty ratio Dav is expressed by the N value (detection frequency) at that time. Even if the minimum average duty ratio Davmin is decreased, it is determined that the actual motor rotational speed MS cannot be decreased to the target motor rotational speed MStg, and the process proceeds to step S307.

That is, the determination values (ΔMSSL, ΔtMSSL, TSL) in step S304, step S305, and step S306 are the actual motor rotation speed MS up to the target motor rotation speed MStg even if the average duty ratio Dav is decreased to the lowest average duty ratio Davmin. In order to determine whether or not it is in a state where it is not possible to lower the value, it is adapted in advance.
In step S307, the energization pattern A for switching the energization mode every electrical angle 60 deg is switched to the energization pattern B for switching the energization mode every electrical angle 120 deg. That is, if the actual motor rotation speed MS cannot be decreased to the target motor rotation speed MStg even if the average duty ratio Dav is decreased to the minimum average duty ratio Davmin, the energization mode (phase in which the pulse voltage is applied) is set. The electrical angle that is the switching cycle is changed in the increasing direction.

FIG. 11 shows the motor torque in the energization pattern A and the motor torque in the energization pattern B at the same average duty ratio Dav.
As shown in FIG. 11, even when the applied voltage is controlled with the same average duty ratio Dav, the motor torque in the energization pattern B is about 3/4 of the motor torque in the energization pattern A. When switching from the current pattern B to the energization pattern B, the motor rotational speed MS decreases toward the target motor rotational speed MStg due to a decrease in motor torque.

That is, when the average duty ratio Dav is reduced to the minimum average duty ratio Davmin, the average duty ratio Dav cannot be further reduced, and the motor rotation speed MS is further reduced from the motor rotation speed MS at that time. However, if the energization pattern A is switched to the energization pattern B, the motor rotation speed MS can be reduced to near the target motor rotation speed MStg.
In the example shown in FIG. 5, when the target rotational speed MStg is MStg1, the actual motor rotational speed MS can be decreased to the target rotational speed MStg1 by reducing the average duty ratio Dav in the energization pattern A.

On the other hand, when the target rotational speed MStg is MStg2, the motor rotational speed MS can be reduced only to the rotational speed MSmin when the average duty ratio Dav is set to the lowest average duty ratio Davmin1, and in the control of the average duty ratio Dav, The motor rotational speed MS cannot be reduced to a lower target rotational speed MStg2.
Therefore, if the motor rotation speed MS cannot be reduced to the target rotation speed MStg2 even if the average duty ratio Dav is reduced to the lowest average duty ratio Davmin1, the current supply pattern A is changed to the current supply pattern B. By switching, the motor torque is reduced, and the rotational speed can be lowered to the target motor rotational speed MStg2, which is a rotational speed lower than the rotational speed MSmin.

Therefore, by switching from the energization pattern A to the energization pattern B, the motor rotation speed MS can be further reduced while maintaining the position information detection cycle and the position information detection accuracy.
After switching to the energization pattern B as described above, the process proceeds to step S308 when it is determined in step S303 that the current energization pattern is the energization pattern B that switches the energization mode every 120 degrees of electrical angle. It becomes like this.

In step S308, it is determined whether or not the absolute value of the control deviation ΔMS is equal to or smaller than a predetermined value ΔMSSLa (ΔMSSLa> 0). If | ΔMS |> predetermined value ΔMSSLa, that is, the motor rotation speed MS is the target motor rotation. In a state where the speed has not reached the vicinity of the speed MStg, this routine is ended as it is, so that the energization mode is continuously switched by the energization pattern B.
On the other hand, if | ΔMS | ≦ predetermined value ΔMSSLa, that is, if the motor rotational speed MS has reached the vicinity of the target motor rotational speed MStg, the process proceeds to step S309 to set a state where | ΔMS | ≦ predetermined value ΔMSSLa. It is determined whether or not it continues for a time TSLcon.

If the state of | ΔMS | ≦ predetermined value ΔMSSLa continues for the set time TSLcon or longer, the actual motor rotational speed MS is stably converged to the target motor rotational speed MStg. In this case, In step S310, if the target rotational speed MStg has not been converged stably, the routine is terminated as it is, and the energization mode B is continuously switched in the energization pattern B.
In step S310, even if it returns to the electricity supply pattern A, it is judged whether the average duty ratio Dav can be made more than the minimum average duty ratio Davmin and can be converged on the target rotational speed MStg.

  If the same torque is generated when the energization mode B is switched to the energization mode A, when the motor torque is proportional to the duty ratio, the average in the energization pattern A with respect to the current average duty ratio Dav in the energization pattern B It is necessary to reduce the duty ratio Dav to 3/4. If the value of 3/4 of the current average duty ratio Dav in the energization pattern B is equal to or higher than the minimum average duty ratio Davmin, the energization is performed even if the current pattern is returned to the energization pattern A. A torque equivalent to the current motor torque in the pattern B can be obtained with a minimum average duty ratio Davmin or more.

If it is determined in step S310 that it is possible to return to the energization pattern A, the process proceeds to step S311 where the energization pattern is switched from the energization pattern B to the energization pattern A, and the electrical angle that is the cycle of switching the energization mode is changed from 120 deg to 60 deg. Switch to.
That is, as shown in FIG. 12, in the speed range where the required average duty ratio for setting the actual motor rotational speed MS to the target motor rotational speed MStg when the energization pattern A is used, the energization pattern is higher than the minimum average duty ratio Davmin. When A is selected and the energization pattern A is selected, the energization pattern B is selected in the speed range where the required average duty ratio for setting the actual motor rotation speed MS to the target motor rotation speed MStg is less than the minimum average duty ratio Davmin. To do.

If it is determined in step S301 that both the target motor rotation speed MStg and the actual motor rotation speed MS are less than the set speed MSSL, the process proceeds to step S312 and N is set to N2 (N2> N1 ≧ 1). Thus, the detection frequency is lowered as compared with the case of proceeding to step S302, and the duty ratio for each PWM cycle is determined according to N2.
When the process proceeds to step S312 than the N value obtained when the process proceeds to step S302, the N value is set to a larger value so that the speed is higher than the set speed MSSL in a speed range lower than the set speed MSSL. The lowest average duty ratio Davmin is lower than that in the region.

Next, in step S313, it is determined whether or not the current energization pattern is the energization pattern B.
When the current energization pattern is the energization pattern B, the process proceeds to step S314 and the subsequent steps, and it is determined in the same manner as in steps S308 to S310 whether or not the energization pattern A can be returned.

In step S314, it is determined whether or not the absolute value of the control deviation ΔMS is equal to or smaller than a predetermined value ΔMSSLa. If | ΔMS |> predetermined value ΔMSSLa, that is, in the state where the target motor rotational speed MStg is not reached. By immediately ending this routine, the energization mode is switched by the energization pattern B.
On the other hand, if | ΔMS | ≦ predetermined value ΔMSSLa, that is, if the target motor rotation speed MStg is reached, the process proceeds to step S315, and a state where | ΔMS | ≦ predetermined value ΔMSSLa continues for the set time TSLcon or longer. It is determined whether or not.

If the state of | ΔMS | ≦ predetermined value ΔMSSLa continues for the set time TSLcon or longer, the actual motor rotational speed MS is stably converged to the target rotational speed MStg. In this case, In step S316, if the target rotational speed MStg has not been converged stably, the routine is terminated as it is, and the energization mode B is continuously switched in the energization pattern B.
In step S316, it is determined whether the average duty ratio Dav can be made equal to or higher than the minimum average duty ratio Davmin and converge to the target rotational speed MStg even after returning to the energization pattern A.

If it is determined in step S316 that it is possible to return to the energization pattern A, the process proceeds to step S317, the energization pattern is switched from the energization pattern B to the energization pattern A, and the electrical angle that is the cycle of switching the energization mode is changed from 120 deg to 60 deg. Switch to.
In the example shown in FIG. 5, when the target rotational speed MStg is set to MStg2, the N value is increased when the target motor rotational speed MStg is switched to MStg3 after switching to the energization pattern B (position information). Since the detection frequency decreases and the minimum average duty ratio Davmin decreases to Davmin2, even when the current pattern A is restored, it can be converged to the target rotational speed MStg3 with an average duty ratio Dav that is equal to or higher than the minimum average duty ratio Davmin2. Then, the energization pattern A is restored.

On the other hand, when it is determined in step S313 that the current energization pattern is the energization pattern A, the process proceeds to step S318 and subsequent steps, and the switching process to the energization pattern B is performed in the same manner as in steps S304 to S307.
In step S318, it is determined whether or not the control deviation ΔMS is equal to or smaller than the negative predetermined value ΔMSSL. If ΔMS> ΔMSSL, it is not necessary to switch from the energization pattern A to the energization mode B, and this routine is terminated as it is. By doing so, the energization control in the energization pattern A is continued.

On the other hand, if ΔMS ≦ ΔMSSL, the process proceeds to step S319, and it is determined whether or not the absolute value ΔtMS of the difference between the current value and the previous value of the actual motor rotation speed MS is equal to or less than a predetermined value ΔtMSSL. It is determined whether or not the rotation speed MS is stagnant in a state higher than the target motor rotation speed MStg.
Here, if ΔtMS> ΔtMSSL, the actual motor rotational speed MS has changed, and may approach the target motor rotational speed MStg in the future. Continue energization control.

On the other hand, if ΔtMS ≦ ΔtMSSL, the actual motor rotational speed MS is stagnant in a state higher than the target motor rotational speed MStg, and the process proceeds to step S320.
In step S320, it is determined whether or not the state where the actual motor rotation speed MS is higher than the target motor rotation speed MStg has continued for a predetermined time TSL or more.

When the state where the actual motor rotation speed MS is higher than the target motor rotation speed MStg has been stagnating for a predetermined time TSL or more, the average duty ratio Dav is expressed by the N value (detection frequency) at that time. It is determined that the actual motor rotation speed MS cannot be reduced to the target motor rotation speed MStg even if the minimum average duty ratio Davmin is decreased, and the process proceeds to step S321.
In step S321, the energization pattern is switched from the energization pattern A that switches the energization mode every electrical angle 60deg to the energization pattern B that switches the energization mode every 120deg electrical angle.

As described above, in the above embodiment, even when the minimum average duty ratio Davmin is reduced due to a decrease in the detection frequency of the rotor position information, the motor rotational speed MS cannot be reduced to the target rotational speed MStg. By switching the energization pattern from the energization pattern A to the energization pattern B, the motor torque can be reduced so that the motor rotation speed MS can be reduced to the target rotation speed MStg.
Therefore, the brushless motor 2 can be controlled at a low rotational speed that cannot be reached only by a decrease in the detection frequency of the rotor position information, and the rotational speed range of the brassless motor 2 can be expanded to the low speed side. it can.

Accordingly, in the case of the brushless motor 2 that drives the electric oil pump 1, the minimum discharge amount of the electric oil pump 1 is reduced, and the power consumption of the brushless motor 2 is unnecessarily increased due to the wasteful discharge amount. In addition, the rotational speed of the electric oil pump 1 can be made as low as possible to reduce pump noise.
When the energization pattern is switched between the energization pattern A and the energization pattern B, if energization is performed with the same average duty ratio Dav, as described above, the torque fluctuation may increase due to increase / decrease in the motor torque. . The torque fluctuation accompanying the switching of the energization pattern can be reduced by changing the duty ratio, and the motor control to which the duty ratio changing process is added will be described with reference to the flowcharts of FIGS.

The routine shown in the flowcharts of FIGS. 13 and 14 adds processing for setting the initial value of the duty ratio after changing the energization pattern based on the duty ratio immediately before switching the energization pattern after the step of switching the energization pattern. 3 and 4 differs from the flowcharts of FIGS. 3 and 4 in that processing for switching the energization pattern is performed in the same manner as the flowcharts of FIGS. 3 and 4.
Therefore, in the flowcharts of FIGS. 13 and 14, steps having the same processing contents as those of the flow charts of FIGS. 3 and 4 are denoted by the same step numbers, and detailed description thereof will be omitted. The accompanying duty ratio changing process will be described.

In the flowcharts of FIGS. 13 and 14, when switching from the energization pattern A to the energization pattern B is set in step S307 or step S321, the process proceeds from step S307 to step S307-2, and from step S321 to step S321-2. Set the changed duty ratio.
When switching from the energization pattern A to the energization pattern B, if the duty ratio is constant, the motor torque decreases. Therefore, changing the duty ratio in the increasing direction suppresses the change in the motor torque decreasing direction. Thus, fluctuations in the motor torque accompanying switching of the energization pattern can be suppressed.

  Here, when switching from the energization pattern A to the energization pattern B with a constant duty ratio, the motor torque decreases to 3/4 (75%), and when the motor torque is proportional to the duty ratio, energization is performed. When the duty ratio after changing the energization pattern is changed to the duty ratio before changing the energization pattern / 0.75 with the change from the pattern A to the energization pattern B, if the duty ratio is increased and corrected, the duty ratio before and after the change of the energization pattern is changed. By making the motor torque substantially constant, it is possible to suppress fluctuations in the motor torque accompanying switching of the energization pattern.

For example, when the duty ratio is calculated by PID control (proportional P, integral I, differential D operation) based on the deviation between the actual motor rotational speed MS and the target motor rotational speed MStg, the switching is performed when the energization pattern is switched. By operating the integral part without changing the proportional part and the differential part before and after, the duty ratio is changed in a direction to suppress the fluctuation of the motor torque accompanying the switching of the energization pattern.
Thereby, the fluctuation | variation of the motor torque accompanying switching of an energization pattern can be suppressed, without reducing the convergence responsiveness to the target rotational speed after switching of an energization pattern.

In the flowcharts of FIGS. 13 and 14, when switching from the energization pattern B to the energization pattern A is set in step S311 or step S317, the process proceeds from step S311 to step S311-2, and from step S317 to step S317-2. Set the duty ratio after changing the energization pattern.
When switching from the energization pattern B to the energization pattern A, the motor torque increases if the duty ratio is constant. Therefore, if the duty ratio is changed in the decreasing direction, the change in the motor torque increasing direction is suppressed. Thus, fluctuations in the motor torque accompanying switching of the energization pattern can be suppressed.

Here, when switching from the energization pattern B to the energization pattern A with a constant duty ratio, the motor torque increases by 25%, and when the motor torque is proportional to the duty ratio, the energization pattern B is changed to the energization pattern. Along with switching to A, if the duty ratio after changing the energization pattern is set to 0.75 before the energization pattern is changed and the duty ratio is corrected to decrease, the motor torque before and after switching the energization pattern is substantially constant. As a result, it is possible to suppress fluctuations in the motor torque accompanying switching of the energization pattern.
If the fluctuation of the motor torque accompanying the switching of the energization pattern can be suppressed as described above, the motor torque can be prevented from temporarily fluctuating greatly with the change of the motor rotation speed, and the followability to the target rotation speed can be improved. Can do.
And in the brushless motor 2 which drives the electric oil pump 1, the rapid change of discharge amount can be suppressed and oil pressure can be controlled stably.

Also, the rectangular wave drive that sequentially switches the selection pattern (energization mode) of the two phases to which the pulse voltage is applied among the three phases in accordance with a predetermined switching timing tends to have a larger torque fluctuation than the sine wave drive. When the energization pattern is switched from the energization pattern A to the energization pattern B in the rectangular wave drive, as shown in FIG. 15, the difference in motor torque before and after the energization mode is switched increases and the torque fluctuation increases.
Here, as shown in FIG. 15, the torque variation in the energization pattern B can be suppressed by delaying the energization mode switching timing from the timing synchronized with the switching timing in the energization pattern A.

In the example shown in FIG. 15, by switching the energization mode in the energization pattern B at a timing delayed by 30 degrees from the energization mode switching timing in the energization pattern A, the torque difference before and after the energization mode switching and the energization The difference between the maximum value and the minimum value of the torque in the pattern B is reduced, and the torque fluctuation in the energization pattern B is reduced.
Note that the angle at which the switching of the energization mode in the energization pattern B is delayed is not limited to 30 degrees, and can be appropriately set as an angle that can sufficiently suppress the torque fluctuation. Moreover, the angle which delays switching of the electricity supply mode in the electricity supply pattern B can be changed according to a motor rotational speed etc., and it can suppress that a torque fluctuation amount changes with respect to the change of a motor rotational speed.

The flowchart of FIG. 16 shows an example of the control for switching the energization mode by delaying the switching timing in the energization pattern B.
In the flowchart of FIG. 16, in step S501, switching from the current energization mode to the next energization mode among basic switching timings (any of 90 deg, 210 deg, and 330 deg) synchronized with the energization mode switching timing in the energization pattern A. It is determined whether or not the timing is detected based on a comparison between the pulse-induced voltage of the non-energized phase and a threshold value.

If it is determined in step S501 that the basic switching timing to the next energization mode has not been detected, the process proceeds to step S503 to continue the current energization mode.
On the other hand, if it is determined in step S501 that the basic switching timing to the next energization mode has been detected, the process proceeds to step S502, after detecting the basic switching timing to the next energization mode, a predetermined angle (for example, 30 deg). It is determined whether or not it has rotated only.

The angular position rotated by a predetermined angle from the basic switching timing is, for example, converted into time based on the motor rotation speed at that time, and rotated by a predetermined angle from the time when the basic switching timing is detected. It can be detected as the timing when only the time required for elapses.
If it is determined in step S502 that the rotation angle after detecting the basic switching timing to the next energization mode has not reached the predetermined angle, the process proceeds to step S503, and the current energization mode is continued.

On the other hand, if it is determined in step S502 that the rotation angle after detecting the basic switching timing to the next energization mode has reached a predetermined angle, the process proceeds to step S504, and the energization mode is switched to the next energization mode.
If the torque fluctuation in the energization pattern B can be suppressed by delaying the switching timing of the energization mode in the energization pattern B as described above, the discharge amount of the electric oil pump 1 can be stabilized and the oil pressure fluctuation can be suppressed. it can.

In the control of the energization pattern shown in the flowcharts of FIG. 3 and FIG. 4 described above, the N value (position information detection frequency) is switched to two types, and the minimum average duty ratio Davmin is set to two levels corresponding to this. However, it is possible to switch the N value to three or more types according to the change in the motor rotation speed, and to switch the minimum average duty ratio Davmin to three or more levels corresponding to this.
The flowcharts of FIGS. 17, 18 and 19 show an example of motor drive control in which the N value is switched to three types according to the change in the motor rotation speed MS, and the energization patterns A and B are set to be switched.

In step 601, it is determined whether or not either the target motor rotation speed MStg or the actual motor rotation speed MS is equal to or higher than the set speed MSSL2.
If either the target motor rotation speed MStg or the actual motor rotation speed MS is equal to or higher than the set speed MSSL2, the process proceeds to step S602, where the target motor rotation speed MStg and the actual motor rotation speed MS are calculated. It is determined whether or not any of them is equal to or higher than the set speed MSSL1 (MSSL1> MSSL2).

If either the target motor rotation speed MStg or the actual motor rotation speed MS is equal to or higher than the set speed MSSL1, the process proceeds to step S603.
In step S603, N is set to N1 (N1 ≧ 1), and the duty ratio for each PWM cycle is determined according to N1.

Next, the process proceeds to step S604 and subsequent steps, and the energization patterns A and B are set. However, since the processing content in each step of step S604 to step S612 is the same as that of step S303 to step S311 in the flowchart of FIG. Then, detailed explanation is omitted.
In general, when the motor rotation speed MS cannot be decreased toward the target rotation speed MStg in the state where the current supply control is performed with the current supply pattern A, the motor rotation speed MS is switched to the current supply pattern B. If the motor torque can be generated with an average duty ratio Dav that is equal to or higher than the lowest average duty ratio Davmin even if it converges to the target rotational speed MStg and returns to the energization pattern A, the energization pattern B is switched to the energization pattern A.

On the other hand, when it is determined in step S602 that the target motor rotational speed MStg and the actual motor rotational speed MS are less than the set speed MSSL1, that is, when the set speed MSSL2 is equal to or higher than the set speed MSSL1, The process proceeds to step S613.
In step S613, N is set to N2 (N2> N1 ≧ 1), the detection frequency is lowered as compared with the case of proceeding to step S603, and the duty ratio for each PWM cycle is determined according to N2. Here, when the value of N is set larger than when proceeding to step S603 (detection frequency is lowered), the minimum average duty ratio Davmin is lowered as shown in FIG.

Next, the process proceeds to step S614 and subsequent steps, and the energization patterns A and B are set. Since the processing contents in steps S614 to S622 are the same as steps S313 to S321 in the flowchart of FIG. Then, detailed explanation is omitted.
Schematically, when the motor rotation speed MS converges to the target rotation speed MStg in the energization pattern B and returns to the energization pattern A, an equivalent motor torque can be generated with an average duty ratio Dav equal to or higher than the minimum average duty ratio Davmin. In the state where the energization pattern B is switched to the energization pattern A and the energization control is performed using the energization pattern A, the energization pattern B is switched to the energization pattern B when the motor rotation speed MS cannot be lowered toward the target rotation speed MStg.

If it is determined in step S601 that the target motor rotation speed MStg and the actual motor rotation speed MS are less than the set speed MSSL2, the process proceeds to step S623.
In step S623, N is set to N3 (N3>N2> N1 ≧ 1), the detection frequency is further reduced as compared with the case of proceeding to step S613, and the duty ratio for each PWM cycle is determined according to N3. Here, when the value of N is set larger than when proceeding to step S613 (detection frequency is lowered), the minimum average duty ratio Davmin is further lowered as shown in FIG.

Next, the process proceeds to step S624 and subsequent steps, and the energization patterns A and B are set. Since the processing contents in steps S624 to S632 are the same as those in steps S313 to S321 in the flowchart of FIG. Then, detailed explanation is omitted.
Schematically, when the motor rotation speed MS converges to the target rotation speed MStg in the energization pattern B and returns to the energization pattern A, an equivalent motor torque can be generated with an average duty ratio Dav equal to or higher than the minimum average duty ratio Davmin. In the state where the energization pattern B is switched to the energization pattern A and the energization control is performed using the energization pattern A, the energization pattern B is switched to the energization pattern B when the motor rotation speed MS cannot be lowered toward the target rotation speed MStg.

Even when the N value is switched to three or more types according to the change in the motor rotation speed, the duty ratio after switching the energization pattern is suppressed from changing the motor torque as shown in the flowcharts of FIGS. In addition, it is possible to change the direction in which the current is applied, and to perform delay processing of the switching timing of the energization mode in the energization pattern B.
By the way, since the torque fluctuation of the energization pattern B is larger than the energization pattern A and the fluctuation of the motor rotation speed tends to be larger, the energization control with the energization pattern B when the fluctuation of the motor rotation speed exceeds the set level. By performing the energization control with the energization pattern A without performing the above, fluctuations in the motor rotation speed can be suppressed.

The flowcharts of FIGS. 21 and 22 show an example of motor control in which it is determined whether or not to perform energization control with the energization pattern B in accordance with fluctuations in the motor rotation speed. Show.
The routine shown in the flowcharts of FIGS. 21 and 22 is obtained by adding a step of determining whether or not the fluctuation of the motor rotation speed exceeds the set level to the flowcharts of FIGS. 3 and 4. Since the steps have the same processing contents as the routines shown in the flowcharts of FIGS. 3 and 4, the steps that perform the same processes as the routines shown in the flowcharts of FIGS. Description is omitted.

In the flowcharts of FIGS. 21 and 22, in step S301, it is determined that either the target motor rotational speed MStg or the actual motor rotational speed MS is equal to or higher than the set speed MSSL, and the process proceeds to step S303. If it is determined that the energization pattern A (switching of the energization mode every 60 deg) is selected, it is determined in step S304-1 whether or not fluctuations in the motor rotation speed (variations exceeding the set level) have been detected. .
The detection of fluctuations in the motor rotation speed will be described in detail later.

If the fluctuation of the motor rotation speed is sufficiently small and the fluctuation of the motor rotation speed is not detected, the process proceeds to step S304 and subsequent steps so long as the motor rotation speed cannot be reduced toward the target. , Switching to energization pattern B (switching of energization mode every 120 deg) is performed.
On the other hand, when fluctuations in the motor rotation speed are detected, that is, when fluctuations in the motor rotation speed in the state where energization control is performed with the energization pattern A exceed the set level, the motor rotation speed is targeted. Even if the current state cannot be lowered, the routine is terminated as it is to suppress further fluctuation in the motor rotation speed by switching to the energization pattern B, and the drive control with the energization pattern A is performed. To continue.

If it is determined in step S303 that the energization pattern B is selected as the energization pattern, the process advances to step S308-1 to determine whether or not a change in the motor rotation speed (a change exceeding the set level) is detected.
If a change in the motor rotation speed is detected, the process proceeds to step S311 to return to the energization pattern A without determining whether the motor rotation speed has converged on the target, thereby reducing the fluctuation in the motor rotation speed. Let

If the energization pattern B is selected and no change in the motor rotation speed is detected, the process proceeds to step S308 and the subsequent steps, the motor rotation speed converges to the target, and the energization is performed. When it is determined that the same motor torque can be generated even if the pattern A is returned, the process for returning to the energization pattern A is performed.
The selection of the energization pattern based on the fluctuation of the motor rotation speed is performed in the same manner when it is determined in step S301 that the target motor rotation speed MStg and the actual motor rotation speed MS are less than the set speed MSSL.

If it is determined that the target motor rotation speed MStg and the actual motor rotation speed MS are less than the set speed MSSL, the process proceeds to step S313, and if it is determined that the energization pattern B is selected, the process proceeds to step S314-1. It is determined whether or not a fluctuation in rotational speed (a fluctuation exceeding the set level) has been detected.
If fluctuations in the motor rotation speed are detected, the process proceeds to step S317 to return to the energization pattern A without determining whether the motor rotation speed has converged on the target, thereby reducing fluctuations in the motor rotation speed. Let

If the energization pattern B is selected and no change in the motor rotation speed is detected, the process proceeds to step S314 and the subsequent steps, the motor rotation speed is converged to the target, and the energization is performed. When it is determined that the same motor torque can be generated even if the pattern A is returned, the process for returning to the energization pattern A is performed.
On the other hand, if it is determined in step S313 that the energization pattern A is selected, the process proceeds to step S318-1, and it is determined whether or not a change in the motor rotation speed (a change exceeding the set level) is detected.

If no change in the motor rotation speed is detected, the process proceeds to step S318 and subsequent steps. If the motor rotation speed cannot be reduced toward the target, switching to the energization pattern B is performed.
On the other hand, when fluctuations in the motor rotation speed are detected, that is, when fluctuations in the motor rotation speed in the state where energization control is performed with the energization pattern A exceed the set level, the motor rotation speed is targeted. Even if the current state cannot be lowered, the routine is terminated as it is to suppress further fluctuation in the motor rotation speed by switching to the energization pattern B, and the drive control with the energization pattern A is performed. To continue.
According to the above control, it is possible to suppress the rotation fluctuation from becoming excessive by selecting the energization pattern B.

  The setting of the energization pattern based on the fluctuation of the motor rotation speed described above can be applied when the N value is switched to three or more types according to the change of the motor rotation speed. The process of changing the ratio in a direction to suppress the fluctuation of the motor torque and the delay process of the switching timing of the conduction mode in the conduction pattern B can be combined with the setting of the conduction pattern based on the fluctuation of the motor rotation speed.

The flowchart of FIG. 23 shows the details of detection of fluctuations in the motor rotation speed.
In step S701, whether or not the absolute value of the difference between the previous value and the current value of the target rotational speed MStg (the amount of change in the target rotational speed MStg per unit time) is within a set value, that is, the target rotational speed MStg is It is determined whether or not there has been a change since the previous time (predetermined time).

If the amount of change in the target rotational speed MStg per unit time is within the set value, the process further proceeds to step S702, and the state in which the amount of change in the target rotational speed MStg per unit time is within the set value is greater than the set time. By determining whether or not it is continuing, it is determined whether or not the target rotational speed MStg is in a stable state holding a constant value.
If it is determined in step S701 that the amount of change in the target rotational speed MStg per unit time exceeds the set value, or if it is determined in step S702 that the duration has not reached the set time, that is, the target If the rotational speed MStg is not in a stable state, the process proceeds to step S705, and variables used for detection of rotational fluctuation (elapsed time ST, angle change integral value IAE described later) are cleared, and then this routine is terminated.

On the other hand, in step S701, it is determined that the amount of change in the target rotational speed MStg per unit time is within the set value, and in step S702, it is determined that the duration exceeds the set time, and the target rotational speed MStg is determined. If is in a stable state, the process proceeds to step S703.
In step S703, it is determined whether the energization pattern currently selected is either energization pattern A (60 deg switching) or energization pattern B (120 deg switching).

When the energization mode is switched in accordance with the energization pattern A, the process proceeds to step S704, where it is determined that there is no fluctuation in the motor rotation speed, and then the variable used for detecting the rotation fluctuation is cleared in step S705. This routine is terminated.
When the energization mode is switched according to the energization pattern A, the motor rotation speed does not fluctuate excessively. When the energization mode is switched according to the energization pattern B, the motor rotation speed varies. Since it may become excessively large, in the case of the energization pattern A, it is determined that there is no rotation fluctuation without detecting the actual rotation fluctuation.

Therefore, the steps S304-1 and S318-1 can be omitted in the flowcharts of FIGS. Even in the case of the energization pattern A, the actual rotation fluctuation can be detected and the presence or absence of the rotation fluctuation can be determined in step S304-1 and step S318-1.
If it is determined in step S703 that the energization pattern B is selected, the process proceeds to step S706, where it is determined whether or not the previous determination result is a determination result that there is a fluctuation in the motor rotation speed.

When the previous determination result is a determination result that there is no fluctuation in the motor rotation speed, the process proceeds to step S707, and the elapsed time ST after the target rotation speed MStg is stabilized is measured.
Next, in step S708, the absolute value AE of the difference between the previous value and the current value of the motor rotation angle, that is, the absolute value AE of the angle change amount per unit time (AE = | current angle−previous angle |) is calculated. .

Further, in step S709, the absolute value AE of the angle change amount is added to the previous integrated value IAE, and the angle change integrated value IAE (IAE = IAEold + AE), which is the integrated value (integrated value) of AE, is updated. .
In step S710, an allowable value OKIAE of the angular change integral value IAE is calculated from the elapsed time ST.
The allowable value OKIAE can be obtained for each elapsed time ST by referring to a table storing the allowable value OKIAE, and can be calculated based on a function f (ST) having the elapsed time ST as a variable. A longer value is set to a larger value.

In the next step S711, the angle change integral value IAE and the allowable value OKIAE (threshold value) are compared, and if IAE <OKIAE, it is determined that there is no fluctuation in the motor rotation speed (the fluctuation is sufficiently small), and this By ending the routine, the determination result indicating no rotation fluctuation is maintained.
On the other hand, if it is determined in step S711 that IAE ≧ OKIAE, the process proceeds to step S712 to switch to a determination result that rotation fluctuation exceeding the allowable level has occurred (rotation fluctuation exists), and the elapsed time. ST and angle change integral value IAE are cleared.

If the previous determination result is a determination result that there is a fluctuation in the motor rotation speed, the process proceeds from step S706 to step S713.
In step S713, the elapsed time ST after the target rotational speed MStg is stabilized is measured.

Next, in step S714, the absolute value AE (AE = | current angle−previous angle |) of the difference between the previous value and the current value of the motor rotation angle is calculated.
Further, in step S715, the absolute value AE of the angle change amount is added to the previous integrated value IAE, and the angle change integrated value IAE (IAE = IAEold + AE), which is the integrated value (integrated value) of AE, is updated. .

In step S716, an allowable value OKIAE of the angular change integral value IAE is calculated from the elapsed time ST.
In step S717, the angle change integral value IAE and the allowable value OKIAE (threshold value) are compared, and if IAE ≧ OKIAE and there is a motor rotation fluctuation, the routine is terminated as it is, thereby causing the rotation fluctuation. Maintain the judgment result.

On the other hand, if it is determined in step S717 that IAE <OKIAE, the process proceeds to step S718, where it is determined whether or not the duration of the state where IAE <OKIAE exceeds the set time.
Here, if the duration of the state where IAE <OKIAE is less than the set time, the routine is terminated as it is to maintain the determination result that there is a rotational fluctuation, and the duration of the state where IAE <OKIAE is set. When the time is exceeded, the process proceeds to step S719 to switch to a determination result that there is no rotation fluctuation (the fluctuation is sufficiently small), and further, the elapsed time ST and the angular change integral value IAE are cleared.

Note that the method for determining the presence or absence of fluctuations in the motor rotation speed is not limited to the method shown in the flowchart of FIG. 23. For example, the presence or absence of rotation fluctuations may be determined based on the amplitude of the motor rotation speed. Can do.
Although the contents of the present invention have been specifically described with reference to the preferred embodiments, it is obvious that those skilled in the art can take various modifications based on the basic technical idea and teachings of the present invention. It is.

Here, technical ideas other than the claims that can be grasped from the above embodiment will be described together with effects.
(A) A brushless motor driving device that switches two phases of three phases to which a pulse voltage corresponding to a pulse width modulation signal is applied according to position information based on a pulse induced voltage induced in a non-energized phase,
A brushless motor driving device that sets an electrical angle, which is a switching period of a phase to which a pulse voltage is applied, to either 60 deg or 120 deg according to the motor rotation speed.
According to the above invention, the motor torque is reduced when the electrical angle that is the switching cycle is set to 60 deg. When the electrical angle is set to 120 deg, the motor rotation speed is decreased by changing the electrical angle from 60 deg to 120 deg. be able to.

(B) A brushless motor driving device that switches two phases to which a pulse voltage corresponding to a pulse width modulation signal is applied among three phases according to position information based on a pulse induced voltage induced in a non-energized phase,
When the electrical angle that is the switching cycle of the phase to which the pulse voltage is applied is set to either 60 deg or 120 deg according to the motor rotation speed, and the electrical angle that is the switching cycle is switched from 60 deg to 120 deg, the duty ratio The brushless motor drive device reduces the duty ratio when the electrical angle that is the switching cycle is switched from 120 deg to 60 deg.
According to the above-described invention, a decrease in motor torque when the electrical angle of the switching cycle is switched from 60 deg to 120 deg is suppressed, and an increase in motor torque when the electrical angle that is the switching cycle is switched from 120 deg to 60 deg is suppressed. The fluctuation of the motor torque accompanying the switching can be suppressed.

(C) A brushless motor drive device that switches two phases to which a pulse voltage corresponding to a pulse width modulation signal among three phases is applied according to position information based on a pulse induced voltage induced in a non-energized phase,
Depending on the motor rotation speed, the electrical angle that is the phase switching period for applying the pulse voltage is set to either 60 deg or 120 deg.
A brushless motor drive device that delays the switching timing of two phases to which a pulse voltage is applied from a timing synchronized with the switching timing when the switching cycle is an electrical angle of 60 deg when the switching cycle is an electrical angle of 120 deg.
According to the said invention, the fluctuation | variation of the motor torque when a switching period is set to 120 degrees of electrical angles can be suppressed.

(D) a brushless motor driving device that switches two phases of three phases to which a pulse voltage corresponding to a pulse width modulation signal is applied according to position information based on a pulse induced voltage induced in a non-energized phase;
Brushless in which the duty ratio of one time per N times (N is an integer of 1 or more) of the pulse width modulation period does not fall below a set value, and the value of N is changed in an increasing direction in accordance with a decrease in motor rotation speed. Motor drive device.
According to the above invention, the position based on the pulse induced voltage is a period in which the duty ratio is not less than the set value by preventing the duty ratio once per N times of the pulse width modulation period from falling below the set value. While information can be acquired, if N is set to 2 or more, a period in which a duty ratio lower than the set value is allowed occurs, the average duty ratio can be lowered, and the motor rotation speed can be lowered.

(E) A brushless motor drive device that switches two phases to which a pulse voltage corresponding to a pulse width modulation signal is applied among three phases according to position information based on a pulse induced voltage induced in a non-energized phase,
The duty ratio of one time per N times of the pulse width modulation period (N is an integer of 1 or more) should not be lower than the set value, and the value of N is changed in the increasing direction according to the decrease in the motor rotation speed.
A brushless motor drive device that changes an electrical angle, which is a switching cycle of a phase to which a pulse voltage is applied, in an increasing direction when the motor rotation speed cannot be reduced by changing the duty ratio.
According to the above invention, by increasing the value of N, the average duty ratio can be lowered and the motor rotation speed can be lowered. However, the rotation speed can be further reduced from the motor rotation speed when the average duty ratio is lowered to the minimum value. When it is desired to decrease, the motor angle is decreased and the motor rotation speed is decreased by changing the electrical angle, which is the switching period of the phase to which the pulse voltage is applied, in the increasing direction.

(F) a brushless motor driving device that switches two phases, to which a pulse voltage corresponding to a pulse width modulation signal is applied among three phases, according to position information based on a pulse induced voltage induced in a non-energized phase;
According to the motor rotation speed, the electrical angle that is the switching cycle of the phase to which the pulse voltage is applied is changed, and when the motor rotation speed fluctuates, the electrical angle that is the switching cycle is changed in a decreasing direction. Motor drive device.
According to the above invention, if the electrical angle that is the switching period of the phase to which the pulse voltage is applied is large, the fluctuation of the motor torque tends to increase and the fluctuation of the motor rotation speed tends to increase. The electric angle of the switching cycle is decreased to reduce the fluctuation of the motor rotation speed.

  DESCRIPTION OF SYMBOLS 1 ... Electric oil pump, 2 ... Brushless motor, 3 ... Motor control apparatus, 212 ... Motor drive circuit, 213 ... Controller, 215u, 215v, 215w ... Winding, 216 ... Permanent magnet rotor, 217a-217f ... Switching element

Claims (3)

Driving a brushless motor having control means for switching a two-phase selection pattern for applying a pulse voltage corresponding to a pulse width modulation signal among three phases according to position information based on a pulse induced voltage induced in a non-energized phase A device,
When the motor rotation speed is reduced, the control means increases the electrical angle that is the switching cycle of the selection pattern when the duty ratio of the pulse width modulation signal is reduced to a set value. The control means performs pulse width modulation control for setting a cycle with a minimum duty ratio capable of acquiring position information based on the pulse induced voltage and a cycle with a duty ratio lower than the minimum duty ratio ,
The brushless motor driving apparatus according to claim 1, wherein the set value is a minimum value of an average duty ratio in the pulse width modulation control.   3. The brushless motor according to claim 1, wherein the control unit switches from an energization pattern that switches the selection pattern in six ways every electrical angle 60 deg to an energization pattern that switches the selection pattern in three ways every electrical angle 120 deg. Drive device.